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Rick Santorum is the only Republican candidate on the campaign trail Sunday

Both Santorum and Ron Paul say they will fight on despite trailing in Nevada

Newt Gingrich said Sunday he is plotting a Southern revival, while Rick Santorum and Ron Paul seek stronger showings in upcoming caucuses to slow front-runner Mitt Romney's momentum after his second straight victory in the Republican presidential race.

Romney's triumph Saturday in the Nevada caucuses, following his convincing triumph last week in Florida, bolstered the perception that the former Massachusetts governor may be unstoppable in his second bid for the GOP nomination.

In Nevada, Romney led with 48% support, while Gingrich had 23% with 18% for Paul and 11% for Santorum, according to incomplete results from vote counters at caucus sites and the state's Republican Party.

The next contests take place Tuesday, with caucuses in Minnesota and Colorado and a non-binding primary in Missouri. Only Santorum, the former Pennsylvania senator who finished last in Nevada, was on the campaign trail Sunday with events in Minnesota.

Gingrich, now firmly lodged as the runner-up to Romney, appeared on two Sunday talk shows to describe a survival strategy aimed at Super Tuesday on March 6, when more than 400 delegates will be at stake.

The 10 contests that day include primaries in Georgia, Gingrich's home state, and neighboring Tennessee -- Southern states that border South Carolina, where Gingrich scored his only victory so far.

"Our goal is to get to Super Tuesday, where we're in much more favorable territory," Gingrich said on the NBC program "Meet the Press" the morning after finishing well behind Romney in Nevada.

Oklahoma, another conservative state where Gingrich hopes to run well, also votes on Super Tuesday, and the former House speaker said he expects to be near Romney in the delegate count after a strong showing on March 6 and the Texas primary in April.

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"My goal will be over the course of February to show that there is a way to change Washington," Gingrich said later on the CBS program "Face the Nation," adding: "I hope by the time we get to Super Tuesday that we'll have made the case that a genuine conservative is a dramatically better choice to defeat Barack Obama than somebody who is in many ways frankly not very distinguishable from President Obama."

Others expressed skepticism that Gingrich can revitalize his chances in the face of Romney's surge since South Carolina's primary.

"There are 17 primaries and caucuses in the next 30 days, and the map is lining up very well for Mitt Romney because here's the bottom line: Everybody knows he's got the best chance to beat President Obama," Virginia Republican Gov. Bob McDonnell said on the CNN program "State of the Union."

Also on CNN, former House Republican leader Dick Armey, who heads the FreedomWorks grassroots conservative group that helped start the tea party movement, said Gingrich's lone primary victory so far was likely to be his last.

"I don't think Newt will be able to replicate that magic moment in South Carolina, because he had a confluence of circumstances that came," Armey said. Romney, meanwhile, "continues to work along at a steady pace, and we are left with a dilemma that we are not going to get a reliable, small-government conservative out of this nominating process."

Texas Rep. Ron Paul, who finished third in the Nevada caucuses, and Santorum said Sunday they would continue their campaigns despite trailing far back because Romney, in Paul's words, "doesn't satisfy a lot of people."

Paul noted on the ABC program "This Week with George Stephanopoulos" that the turnout Saturday in Nevada was lower this year than in 2008, when Romney also won the state. A similar lower turnout in Florida this year compared to four years earlier has raised questions about whether Republican voters are unhappy with their choices.

Santorum, meanwhile, said on "Fox News Sunday" that both Romney and Gingrich are too similar to Obama on major issues such as health care reform, climate change and Wall Street bailouts, while his record is the only one representing true conservative principles that contrast with Obama's policies and record.

"This race is a long, long way from being over," Santorum said. "As people see Romney doing well and Gingrich not up to the task with money, resources and organization, they're looking for someone else who can take on Mitt Romney. And more importantly who can take on Barack Obama."

Santorum also rejected any assertion that this week's contests represented a make-or-break moment for his campaign.

Noting that Romney and Paul had an advantage in the primaries and caucuses so far because they both ran in 2008, Santorum said: "Now we're getting to the states where people don't have the natural advantage, don't have the time commitment, the staff commitment to really build an organization like they did in these first five."

In particular, Santorum pointed out that his chief rival for conservative votes -- Gingrich -- failed to get his name on the ballot in Missouri.

"I think we're going to do very well here in Minnesota," Santorum said. "I think we're going to do very well in Colorado, and we've got a one-on-one matchup against Mitt Romney in Missouri."

The bitter campaign, especially between Romney and Gingrich, has caused concern among some Republicans that attack ads funded in part with millions of dollars from outside groups will damage the survivor's chances against Obama in November.

On Saturday night, in a news conference after his drubbing by Romney in Nevada to negate rumors he would withdraw, Gingrich unleashed another vitriolic fusillade.

"If you can't tell the truth as a candidate for president, how can the country possibly expect to you lead as president?" Gingrich said of Romney. "And I frankly was stunned, I make no bones about this, in the second Florida debate, I had nothing to say because I had never before seen a person who I thought of as a serious candidate for president be that fundamentally dishonest and it was blatant and it was deliberate and he knew he was doing it."

Armey said such outbursts helped no one, including Gingrich.

"I think he's digressed into a state of taking a second-rate campaign and turning it into a first-rate vendetta," Armey said on CNN, later adding: "I thought that last night was really sad for him, and quite frankly, again, so much of Newt's whole life is overstates. He overstates the case in a hyperbolic fashion. It just looks vindictive."

Romney was the main target of Paul and Santorum, however. Paul got in a dig when asked if he might be able to persuade Romney to adopt some of Paul's libertarian positions on key issues as the nomination process proceeds.

With a dedicated base of mostly young supporters, Paul could represent a valuable voting bloc if the outcome of the nomination race remained undecided at the August convention.

"Yeah, I think Mitt could change his mind. He's changed his mind in the past," Paul said, referring to Romney's shift to more conservative stances since his years as Massachusetts governor. "If he hears from our young people and voters and we continue this, yeah, he's going to change his mind, if there's a political benefit to it."

Santorum referred to Romney as a "uni-dimensional candidate" on Fox, while on CBS, former New York Mayor Rudy Giuliani cited Romney's past changes on issues as a reason for his inability to win more than 50% support in any contest so far.

"He has changed his position on virtually everything," said Giuliani, who has not yet endorsed anyone for the GOP nomination. "He was a traditional moderate Republican -- strong on fiscal matters, conservative, strong on foreign policy but basically socially moderate -- and he changed all that."

In the early primary and caucus states, Romney polled low among those who self-identified as tea party supporters, while Gingrich drew much of the momentum for his South Carolina primary victory from activists within the grassroots movement.

Recent primaries show the tables have turned. In entrance and exit polls from the Florida and Nevada contests, Romney climbed considerably in support among the tea party base, garnering 39% of the voting bloc in Nevada to Gingrich's 30%.

Armey, however, said he would support Romney if the former governor ends up competing against Obama in the fall.

"We would rather have a Republican president that's not fully the guy we adore wanting our affections than a Democrat president who despises us and covets the affections of our mortal enemies on public policy," Armey told CNN.